https://www.sciencedirect.com/science/article/abs/pii/S0048969724004819
"Due to high-population density, frequent close contact, possible poor
ventilation, university classrooms are vulnerable for transmission of
respiratory infectious diseases. Close contact and long-range airborne are
possibly main routes for SARS-CoV-2 transmission. In this study, taking a
university classroom in Beijing for example, close contact behaviors of
students were collected through a depth-detection device, which could detect
depth to each pixel of the image, based on semi-supervised learning. Finally,
23h of video data were obtained. Using Computational Fluid Dynamics, the
relationship between viral exposure and close contact behaviors (e.g.
interpersonal distance, relative facial orientations, and relative positions)
was established. A multi-route transmission model (short-range airborne, mucous
deposition, and long-range airborne) of infectious diseases considering real
close contact behaviors was developed. In the case of Omicron, the risk of
infection in university classrooms and the efficacy of different interventions
were assessed based on dose-response model. The average interpersonal distance
in university classrooms is 0.9m (95% CI, 0.5m–1.4 m), with the highest
proportion of face-to-back contact at 87.0%. The risk of infection of
susceptible students per 45-min lesson was 1%. The relative contributions of
short-range airborne and long-range airborne transmission were 40.5% and 59.5%,
respectively, and the mucous deposition was basically negligible. When all
students are wearing N95 respirators, the infection risk could be reduced by
96%, the relative contribution of long-range airborne transmission increases to
95.6%. When the fresh air per capita in the classroom is 24m3/h/person, the
virus exposure could be decreased by 81.1% compared to the real situation with
1.02m3/h/person. In a classroom with an occupancy rate of 50%, after optimized
arrangement of student distribution, the infection risk could be decreased by
62%."
Via Diane A, who wrote:
The risk of infection of susceptible students per 45-min lesson was 1%.
(That adds up fast with 15 classes/week for many students.)
An occupancy rate of 50% reduced infection risk by 62%.
Fresh air decreased risk by 81.1%.
All students wearing N95 respirators reduced risks by 96%.
So, which of these mitigations are we doing to protect students? None. We
are doing none of them.
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
